// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SPDY_HPACK_OUTPUT_STREAM_H_
#define NET_SPDY_HPACK_OUTPUT_STREAM_H_

#include <stddef.h>
#include <stdint.h>

#include <map>
#include <string>

#include "base/macros.h"
#include "base/strings/string_piece.h"
#include "net/base/net_export.h"
#include "net/spdy/hpack/hpack_constants.h"

// All section references below are to
// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08

namespace net {

// An HpackOutputStream handles all the low-level details of encoding
// header fields.
class NET_EXPORT_PRIVATE HpackOutputStream {
public:
    explicit HpackOutputStream();
    ~HpackOutputStream();

    // Appends the lower |bit_size| bits of |bits| to the internal buffer.
    //
    // |bit_size| must be > 0 and <= 8. |bits| must not have any bits
    // set other than the lower |bit_size| bits.
    void AppendBits(uint8_t bits, size_t bit_size);

    // Simply forwards to AppendBits(prefix.bits, prefix.bit-size).
    void AppendPrefix(HpackPrefix prefix);

    // Directly appends |buffer|.
    void AppendBytes(base::StringPiece buffer);

    // Appends the given integer using the representation described in
    // 6.1. If the internal buffer ends on a byte boundary, the prefix
    // length N is taken to be 8; otherwise, it is taken to be the
    // number of bits to the next byte boundary.
    //
    // It is guaranteed that the internal buffer will end on a byte
    // boundary after this function is called.
    void AppendUint32(uint32_t I);

    // Swaps the interal buffer with |output|.
    void TakeString(std::string* output);

private:
    // The internal bit buffer.
    std::string buffer_;

    // If 0, the buffer ends on a byte boundary. If non-zero, the buffer
    // ends on the most significant nth bit. Guaranteed to be < 8.
    size_t bit_offset_;

    DISALLOW_COPY_AND_ASSIGN(HpackOutputStream);
};

} // namespace net

#endif // NET_SPDY_HPACK_OUTPUT_STREAM_H_
